2025 SSMO Relay Round 4 Problems/Problem 3

Problem

Let $T = TNYWR.$ A particle moves in the coordinate plane such that at any time $t,$ its position is \[\left(\sum_{a=1}^{T-1} \cos(at),\sum_{a=1}^{T-1} \sin(at)\right).\] Over the time interval $t\in(0,k],$ the particle lies on at least one coordinate axes $T$ times. If the minimal value of $k$ can be written as $\frac{m\pi}{n}$ for relatively prime positive integers $m$ and $n,$ find $m+n$.

Solution